Hydraulic radial piston machine

Abstract

A hydraulic radial piston machine for stepplessly displaceable piston stroke has a plurality of pistons which are formed as roller bodies and abut linearly with their circular spherical regions against a control curve which is formed on a control ring displaceable relative to a cylinder body of the machine, wherein the control curve is formed as a symmetrical spatial curve such that the curve regions which form both the inner dead point for the pistons and the outer dead point for the pistons change in the displacement direction of the control ring.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims: 
     
       1. A hydraulic radial piston machine with steplessly adjustable piston stroke, comprising a control pin; a rotatable cylinder body arranged concentrically to said control pin and having a plurality of openings; a plurality of pistons which are formed as rolling bodies and distributed symmetrically over a periphery of said cylinder body in said openings; and means forming a control curve which is displaceable relative to said cylinder body and over which said pistons roll, said pistons having a circular cylindrical region which linearly abut against said control curve, said pistons being arranged in said cylinder body tiltably with their axes of rotation in a relatively small angular region; and a control ring axis-parallel with and displaceable relative to said cylinder body, said control curve being formed on said control ring as a symmetrical spatial curve such that said pistons are tilted by said curve within said openings, and the curve regions which form both an inner dead point for said pistons and an outer dead point for said pistons change in direction of displacement of said control ring. 
     
     
       2. A hydraulic radial piston machine as defined in claim 1, wherein said control ring concentrically surrounds said cylinder body and has an inner side, said control curve being formed on said inner side of said control ring, said control ring having two end sides; and further comprising spring means engaging with one end side of said control ring so that said control ring is displaceable in an axial direction against the force of said spring means. 
     
     
       3. A hydraulic radial piston machine as defined in claim 1, wherein said circular cylindrical central region of each of said pistons has two ends, each of said pistons being provided with a spherical portion at each of said ends of said central portion. 
     
     
       4. A hydraulic radial piston machine with steplessly adjustable piston stroke, comprising a control pin; a rotatable cylinder body arranged concentrically to said control pin; a plurality of pistons which are formed as rolling bodies and distributed symmetrically over a periphery of said cylinder body; and means forming a control curve which is displaceable relative to said cylinder body and over which said pistons roll, said pistons having a circular cylindrical region which linearly abut against said control curve, said pistons being arranged in said cylinder body tiltably with their axes of rotation in a relatively small angular region; and a control ring axis-parallel with and displaceable relative to said cylinder body, said control curve being formed on said control ring as a symmetrical spatial curve such that the curve regions which form both an inner dead point for said pistons and an outer dead point for said pistons change in direction of displacement of said control ring, said circular cylindrical central region of each of said pistons having two ends, each of said pistons being provided with a spherical portion at each of said ends of said central portion and having a predetermined cross-section, said cylinder body having a plurality of openings for receiving said pistons, said cylinder openings having a diameter corresponding to said axial cross-section of said pistons. 
     
     
       5. A hydraulic radial piston machine with steplessly adjustable piston stroke, comprising a control pin; a rotatable cylinder body arranged concentrically to said control pin and having a plurality of openings; a plurality of pistons which are formed as rolling bodies and distributed symmetrically over a periphery of said cylinder body within said openings; and means forming a control curve which is displaceable relative to said cylinder body and over which said pistons roll, said pistons having a circular cylindrical region which linearly abut against said control curve, said pistons being arranged in said cylinder body tiltably with their axes of rotation in a relatively small angular region; and a control ring axis-parallel with and displaceable relative to said cylinder body, said control curve being formed on said control ring as a symmetrical spatial curve such that the curve regions which form both an inner dead point for said pistons and an outer dead point for said pistons change in direction of displacement of said control ring, said control ring concentrically surrounding said cylinder body and has an inner side, said control curve being formed on said inner side of said control ring, said control ring having two end sides; spring means engaging with one end side of said control ring so that said control ring is displaceable in an axial direction against the force of said spring means; a housing; a ring disc arranged coaxially rotatable in said housing, said one side of said control ring being provided with blind openings having bottoms, and said spring means including helical pressure springs arranged between said bottoms of said blind holes of said control ring on the one hand and said ring disc on the other hand. 
     
     
       6. A hydraulic radial piston machine with steplessly adjustable piston stroke and formed as a hydraulic motor, comprising a control pin; a rotatable cylinder body arranged concentrically to said control pin and having a plurality of openings; a plurality of pistons which are formed as rolling bodies and distributed symmetrically over a periphery of said cylinder body within said openings; and means forming a control curve which is displaceable relative to said cylinder body and over which said pistons roll, said pistons having a circular cylindrical region which linearly abut against said control curve, said pistons being arranged in said cylinder body tiltably with their axes of rotation in a relatively small angular region; and a control ring axis parallel with and displaceable relative to said cylinder body, said control curve being formed on said control ring as a symmetrical spatial curve such that the curve regions which form both an inner dead point for said pistons and an outer dead point for said pistons change in direction of displacement of said control ring; a housing; a plurality of guiding pins mounted in said housing and each provided with a guiding roller supported thereon, said control ring being axially displaceable and rotatable in said housing and having a circular cylindrical outer surface provided with a plurality of helically extending guiding grooves which are uniformly distributed over its periphery, said guiding pins with said guiding rollers extending into said guiding grooves. 
     
     
       7. A hydraulic radial piston machine as defined in claim 6, wherein each guiding groove has two groove portions connected with one another in a connecting point and extending in both peripheral directions from said point with equal pitch angles. 
     
     
       8. A hydraulic radial piston machine as defined in claim 6, wherein said control pin is coupled with said control ring so that it rotates with the latter. 
     
     
       9. A hydraulic radial piston machine as defined in claim 6, wherein said ring disc has at least one driving pin extending into one of said helical pressure springs, said ring disc also having a driving projection, said control pin being arranged floatingly and having a radially projecting web which abuts against said driving projection.